This type of retaining device for a vehicle door is disclosed in, for example, the following Patent Document 1. In the following Patent Document 1, the movable wedge (described as wedge) and the stationary wedge (described as striker) are provided separately from a vehicle door lock device (in the following Patent Document 1, illustration and description are omitted). Note that, the vehicle door lock device generally includes a door lock striker to be assembled to an end surface on a vehicle body opening side, and a door lock assembly to be assembled to an end surface on a vehicle door side (the door lock assembly including a latch engageable/disengageable with respect to the door lock striker). When the latch is held in an engaged state with the door lock striker, an opening part (vehicle body opening) provided in the vehicle body is closed by the vehicle door (door closing state).